New Vintage HP Junk for Me!

[Mr. Coffee]

I'm addicted to old HP AC millivolt meters. My newest resto job was this 400C model. Stated bandwidth is 20 Hz to 2 MHz, 1 mV to 300 V full scale--but anyone will tell you that's conservative. This particular unit reads flat dead nuts accurate to about 3 MHz.

Great for setting audio amplifier gain or MW RF work. You can hook the test leads to an antenna and the output of the amplifier (the upper right pair of binding posts) to a diode and headphones and listen to radio broadcast.

There are ten tubes inside.



cheers
Rob

[robrenz]

Nice restore job   I have the same disease

[Mr. Coffee]

Thanks, they are pretty amazing instruments even today. Handy on the workbench. When I'm feeding a sinewave from a signal generator to test gain or frequency response they are a lot easier to use than a scope, in my opinion. Sometimes, all I need is (sine) RMS voltage and that needle swing is pretty easy to interpret. 

[SoundTech-LG]

A pic of my HP milli Ammeter. Zero tubes inside! No model # on it either, but it looks a a lot like that 400C. Me thinks it might be internal company test equipment used in Palo Alto. Anyone see one of these before? clue to vintage?

[Bored@Work]

A pic of my HP milli Ammeter. Zero tubes inside! No model # on it either, but it looks a a lot like that 400C. Me thinks it might be internal company test equipment used in Palo Alto. Anyone see one of these before? clue to vintage?

Looks more like someone fitted an HP meter movement in some other enclosure. Maybe a repair job, a frankenstein.

[SoundTech-LG]

Well dude, it's not my job to prove anything to you, but I can easily open it up again to show you (photos) of the innards, ALL HP inside, and does not look hacked. The main thing to consider here is the meter face. Just browse all the old HP catalogs. You will NOT find that meter face anywhere, on any HP models. Most likely internal Factory use only test equipment. That's not so hard to believe now, is it???

[SoundTech-LG]

Sent photos to Ken Kuhn.

Ken's opinion...    Internal use Test Equipment.

http://www.kennethkuhn.com/hpmuseum/